Connecting Garden Hose to Pressure Tank Line

[Bannerman]

like calling my posts 'garbage in garbage out' and 'shell games':

You are asking for advice but we are not there to see for ourselves so as to provide a knowledgeable answer.

A garden hose will be usually 1/2" or 5/8" diameter and flow will usually be further restricted through a sprinkler or hand nozzle.. Although 3/4" PEX will have a smaller inner diameter compared to other pipe material, teeing off the 3/4" PEX line to supply the garden hose bib should not then result in much if any a flow reduction to the garden hose.

Since it seems you will need to install an exterior garden hose bib, obtain one equipped with a vacuum breaker. If there is a loss of supply pressure, water will not be syphoned from the hose as the vacuum breaker will allow air to enter at the bib .

 

[LLigetfa]

I want to use untreated water for the garden hoses.

You probably could not draw 5 GPM from a single garden hose but since you say "hoses" plural, we have to guess how many GPM you might draw at once. At my house I had four hose bibs connected to timers set so that they all run at the same time to reduce pump cycling. They are connected before the water conditioning equipment and the reverse flow it caused was enough to disturb the media pack. Other folks that have sprinkler systems have reported the same problem that was solved with a check valve.

A pulse meter does not know what direction the water flows through it. Your water treatment system and the house plumbing have elastic potential so as the well pump pressure cycles up and down, there might be enough flow past the pulse meter to register and dispense chlorine even when there is no water consumption in the house. This sort of "breathing" is also known to produce false consumption on metered softeners.